How Can We Make the Malicious Browser Benchmark Trick

"The old malicious browser benchmark trick" seen in Mr robot's Season 2 Episode 8 ... She used this web page and I remember seeing mp4 file in the command line from the girl's PC.

Anyone can help me here with what that website does and how can we do something like that ? ..

I never knew you could make a payload on a webpage and get a connection from it.